Effects of the second virial coefficient on the adiabatic lapse rate of dry atmospheres

We study the effect of the second virial coefficient on the adiabatic lapse rate of a dry atmosphere. To this end, we compute the corresponding adiabatic curves, the internal energy, and the heat capacity, among other thermodynamic parameters. We apply these results to Earth, Mars, Venus, Titan, and the exoplanet G1 851d, considering three physically relevant virial coefficients in each case: the hard-sphere, van der Waals, and the square-well potential. These examples illustrate under which atmospheric conditions the effect of the second virial coefficient is relevant. Taking the latter into account yields corrections towards the experimental values of the lapse rates of Venus and Titan in some instances.Comment: 12 pages, 8 figures. Comments are welcom

La noción aristotélica de ciudadano: una realización ético-política

En el trabajo se presentó la noción aristotélica de ciudadano, caracterizada como realización ético-política del hombre, para alcanzar la eudaimonía (felicidad) o buen vivir. La investigación se desarrolló a partir de un enfoque epistemológico hermenéutico con el que se analiza la propuesta filosófica de Aristóteles contenida principalmente en los textos Ética Nicomáquea y Politeía. El presupuesto básico de esta interpretación parte de la asunción aristotélica del hombre como un ser dotado de lógos, de una racionalidad amplia que lo conduce al uso del lenguaje, a la articulación de sentido y, por tanto, a la construcción de la vida en sociedad. Este lógos, como fuerza creadora y horizonte de la naturaleza humana, se expresa en la deliberación ética y política que forma el criterio necesario para actuar en la vida según las virtudes que lo acerquen al fin propuesto: su felicidad. Pero la felicidad del hombre es una realización conjunta entre los miembros de la pólis, es, entonces, una realización intersubjetiva. La pólis constituye el escenario físico e inmaterial en que el ciudadano participa de la vida pública, entre otros ciudadanos, libres e iguales en virtud, para llevar a cabo una vida plena 1) en ejercicio de la phrónesis (traducida como “prudencia”), que es la virtud suprema del uso práctico del intelecto y; 2) participando de las magistraturas como característica principal de la ciudadanía; según 3) un sentido de justicia social garantizado por el “imperio de la ley” como la mejor politeí

Enclosed poche and the construction of the void

ilustraciones, fotografías, graficasEl término poché, un concepto habitualmente usado en los talleres de arquitectura de la escuela de bellas artes de París del Siglo XVIII hacía referencia a la técnica empleada por los arquitectos con el objetivo de achurar con tinta, la sección de los muros en planta, así como algunos espacios auxiliares que los mismos consideraban prudente ocultar del dibujo. Por el contrario, el vacío, un espacio preponderante en la composición arquitectónica dada su relevancia social, era resultante de esta operación, en la que el programa definía la forma y la secuencia espacial. No resulta desacertado pensar en la inversión del paradigma poché ya que la reflexión estructurante de este trabajo final de maestría está orientada a la construcción de espacios intermedios, colectivos, que funcionen de manera no reglada y tengan origen en el vacío. En ese sentido, lo no reglado prima sobre lo programado buscando la prefiguración de este último a través de una operación dual de lleno/vacío, programa/no programa, ambivalencia que sirve para la delimitación del espacio intermedio y el ámbito contenido. A través de un objeto arquitectónico con uso educativo, son puestas en práctica, estrategias de agrupación, concatenación y deslizamiento que resuelven el espacio intermedio al interior del edificio y su respectivo poché contenedor programado. Un mundo dentro de otro mundo. (Texto tomado de la fuente)Poche, commonly used in École des Beaux-Arts architecture workshops during the 18th century, as a technique that consists to fill in ink, the section of the walls in plan as well as some auxiliary spaces the architect considered reasonable to hide from the drawing. In the other way, the void, as an important collective space, was the result of the concatenation, sliding and grouping operation, that gives shape to the interior space and it’s poche. It is right to think to reverse the poche paradigm so this final master's project aims towards the construction of the –in between-, collective spaces, working without a fixed program where the void is its origin. In this sense, the unregulated prevails over the programmed, seeking its prefiguration through a dual operation of emptiness/filled, program/non-program, ambivalence as a function to delimit the intermediate space and the contained enclosure. In this case, through an architectural object with educational use and, on a smaller scale, commercial use, the interaction of the building with the urban space, gives rise to concatenation, sliding and grouping strategies that resolve the intermediate space and its poche programmed inside the building. A world inside another world.MaestríaMagíster en Arquitectur

Biomechanics of the Cornea Assessed by the CorVis ST ® Device: a Numerical Approach

To evaluate by means of finite element modeling the influence of tissue properties of the cornea on its deformation response when an air jet is applied onto its surface and, according to this, to discuss the clinical interpretation of these measurements in terms of corneal biomechanical behaviour

Déjà vu

Cuentan que en 1964 Charles Dotter, tras haber realizado su primera angioplastia que salvó la pierna de la buena señora octogenaria, supongo que de Oregón, a veces recibía notas de “ver pero no tocar”. En los formularios de petición procedentes de otros departamentos del Hospital de Portland, detrás de “Angio left femoral arterio-gram” se podía leer en mayúsculas y subrayado: “Visualize but do not try to fix”..

Adiabatic lapse rate of real gases

We derive a formula for the dry adiabatic lapse rate of atmospheres composed of real gases. We restrict our study to those described by a family of two-parameter cubic equations of state and the recent Guevara-Rodríguez noncubic equation. Since our formula depends on the adiabatic curves, we compute them all at once, considering molecules that can move, rotate, and vibrate, for any equation of state. To illustrate our results, we estimate the lapse rate of the troposphere of Titan, obtaining a better approximation to the observed data in some instances, when compared to the estimation provided by the virial expansion up to the third order.B.D. acknowledges support from the CONEX-Plus programme funded by the Universidad Carlos III de Madrid and the European Union's Horizon 2020 research and innovation program under Marie Sklodowska-Curie Grant No. 801538. J.E.R. acknowledges financial support from the Consejo de Ciencia y Tecnología del Estado de Puebla. This work has been supported by the Spanish Ministerio de Ciencia Innovación y Universidades-Agencia Estatal de Investigación under Grant No. PID2020-116567GB-C22

Computational planning tools in ophthalmology: Intrastromal corneal ring surgery

This thesis addresses the problem of the simulation of intrastromal corneal ring segment surgery for the reduction of myopia and astigmatism, as well as the stabilisation of keratoconus (KC). This disease causes high myopia, irregular astigmatism and reduction of the patient's visual acuity to the point of blindness. Therefore there are several techniques to try to stabilise it and, thus, prevent its progression. For mild keratoconus, it is enough to use special spectacles or lenses to try to correct it, but in more advanced cases it would be necessary to use refractive surgery to try to stop the progression of the disease. The most common ones to avoid the cornea transplant (PK) are the cross-linking and the additive surgery of intrastromal rings. The current planning tools are empirical, based on the nomograms of the ring manufactures, and rely on the experience of the surgeon. Unfortunately, deterministic tools able to estimate the postsurgical visual results of this treatment do not exist. Therefore, the aim of the current thesis is to establish a realistic numerical framework to simulate intrastromal ring surgeries and estimate the mechanical and optical postsurgical outcomes. There are different types of rings depending on their angle and cross-section. There are two large groups of rings: segments which have an angle of less than 360º and those that cover the entire circumference. In the first group we find rings of triangular section such as the Keraring (Mediaphacos, BeloHorizonte, Brazil) and the Ferrara (AJL Ophthalmic Ltd, Spain) and rings of hexagonal section like the Intacs (Additional Technology Inc.). In the second group we can find the MyoRing (Dioptex, GmbH.) whose cross-section is the combination of a parabola and a circumference and the Intacs SK whose section is oval. Due to the complexity of the simulation, since multiple variables are involved, such as the type of rings, the model of the corneal material, the contact conditions between them, etc., two methodologies arised which simulated the insertion of the rings. Both are based on generating a hole in the corneal stroma, introducing the ring and closing the hole with the ring inside, establishing contact until the simulation is completed. In the first of the methodologies the hole was generated by introducing a pressure, while the second was used to an auxiliary tool, such as balloon angioplasty to introduce endovascular stents, which is displaced generating enough hole to insert the rings. As with all numerical simulations, they were not exempt of limitations, although with the first of the methodologies only circular cross--section rings were simulated and in some configurations, there was pressure inside the hole, so it was decided to focus on the second. Nevertheless, interesting conclusions were obtained: the greatest correction was obtained by placing the rings with the largest section near the apex, and whether the ring is located near the epithelium, the stresses generated in the stroma can cause the ring to extrude. With the second methodology based on a displacement control, it was possible to simulate most of the cross-sections and very interesting studies were carried out that gave conclusive results. The most important were: i) the most influential parameter is the depth of insertion; ii) considering the physiological depth of the surgery, the greater optical change is provided by the diameter of the ring, and the fine adjusted is reached with the size of the implant cross--section, i.e the diameter of the implant and the size of the cross--section are the key on regulating the refractive correction; iii) the friction between ring and stroma is important to consider it because a prediction of 2 or 3 diopters could be lost; iv) whether the KC progression is stress-driven, only MyoRing can stop its progression; v) when the covered arc of the segments is more than 320º, axisymmetric model could be used instead of tridimensional model, saving computational time; vi) the anisotropy of the model does not play an important role because the rings are much stiffer than corneal tissue; vii) the implants cannot consider such as second limbus since they act as a dynamic pivot that moves along the circadian cycles of intraocular pressure (IOP); viii) preliminary nomograms is built which allow the estimation of the optical outputs according to the size and typology of the ring and optical zone of implantation.Additionally, a characterisation of ring material was carried out by means two complementary methods: uncertainty analysis and iFEM optimisation, concluding that the manufacturing process of the rings could be the cause of the alteration of the material between the raw PMMA and the ring already prepared for its insertion.<br /

Estudio sistemático de la estabilidad biomecánica de lentes intraoculares C-loop: Enfoque a un diseño óptimo de los hápticos

El objetivo de este Trabajo Fin de Máster es estudiar la influencia de los parámetros que definen la geometría de las lentes intraoculares C-loop que afectan a la estabilidad mecánica en el saco capsular. Dando lugar a un diseño óptimo de lentes C-loop que minimiza el desplazamiento axial, la inclinación y la rotación.Se estudiaron un total de 144 variaciones geométricas de una lente intraocular C-loop no angulada. El conjunto de variaciones adecuado se determinó mediante un análisis factorial mixto, que permitió analizar el impacto de los diferentes diseños sobre la estabilidad mecánica de la lente (fuerza de compresión, desplazamiento axial, inclinación y rotación). Los parámetros de diseño estudiados fueron: la longitud, anchura, espesor y ángulo de apertura del háptico, la unión háptico-óptica y el inicio de la curvatura háptica. El impacto de los diferentes parámetros se evaluó mediante gráficos de Pareto y análisis estadísticos.La fuerza de compresión (o reacción) se ve afectada por la anchura del háptico, la unión háptico-óptica y la interacción entre ambas. El desplazamiento axial se ve afectado principalmente por la anchura y el grosor del háptico, así como por el tamaño de la unión háptico-óptica. La inclinación se ve afectada por el espesor háptico y la interacción entre la curvatura háptica y la unión háptico-óptica. La rotación se ve afectada por el inicio de la curvatura háptica, la unión háptico-óptica y la anchura del háptico. La principal conclusión de este TFM es que la unión háptico-óptica es uno de los parámetros más influyentes que afectan en las cuatro respuestas estudiadas de las lentes C-Loop. Cuanto más pequeña sea la unión háptico-óptica, mejor será la estabilidad biomecánica.<br /

Energy-Efficient Routing Protocol for Selecting Relay Nodes in Underwater Sensor Networks Based on Fuzzy Analytical Hierarchy Process

The use of underwater sensor networks (UWSNs) offers great advantages in many automatic observation services such as water monitoring (ocean, sea, etc.) and registering of geological events (landslides, earthquakes). However, UWSNs have many more limitations than terrestrial sensor networks (smaller bandwidth, higher delays, etc.) with new requirements such as low power consumption by nodes or being able to select appropriate routes in a dynamic topology due to water currents and movements. To cope with these problems, the use of a routing protocol is very important. In this paper we propose a routing technique that adapts to changes in the network topology, avoiding multiple retransmissions that would affect its overall performance. This protocol is energy-efficient and is implemented using a fuzzy analytical hierarchical process (FAHP) under multi-criteria decision making (MCDM) to make an intelligent routing decision based on objectives, criteria and alternatives. To select the next node on the route, several comparison matrices are used: number of hops, distances to the sink node, and number of neighbors. The results show that the proposed setup behaves similarly to other existing underwater sensor network routing schemes using fuzzy schemes such as SPRINT.This research was funded in part by the Spanish Ministry of Science and Innovation through the project “NAUTILUS: Swarms of underwater autonomous vehicles guided by artificial intelligence: its time has come” (Grant: PID2020-112502RB/AEI/10.13039/501100011033). Partial funding for open access charge: Universidad de Málag